1. Field of the Invention
The present invention relates to an Internet Protocol Version 6 (IPv6) based Low Power Wireless Personal Area Network (LoWPAN) and, in particular, to a mobility management system and method for a LoWPAN.
2. Description of the Related Art
Unlike the IP-based Local Area Network (LAN) and Wide Area Network (WAN), a Personal Area Network (PAN) is a simple low cost communication network that allows wireless connectivity in application with limited power and relaxed throughput requirements. An Internet Protocol V6 (IPv6) based Low Power Wireless Personal Area Network (referred to herein as 6LoWPAN) is a wireless communication network implemented with connectivity to IP network by adding a gateway to the LoWPAN, and many researches and standardization efforts for efficient packet transmission over 6LoWPAN have been done.
Meanwhile, recent communication systems are designed such that end devices maintain their connections to the system while moving among networks, or routers. Particularly with respect to the 6LoWPAN, there have been various Network Mobility (NEMO) techniques proposed for a mobile router to support the mobility of the nodes in a 6LoWPAN. With a NEMO, the mobile router enables a node to access the Internet via a wireless access network such as Wireless Local Area Network (WLAN), which may be based on the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standard.
FIG. 1 is a schematic diagram illustrating a conventional network architecture including a 6LoWPAN node showing access to an IP network from the 6LoWPAN.
In FIG. 1, nodes of 6LoWPANs 101, 103, which represent typical of 6LoWPANs, access an conventional IPv6 network via access networks 102 and 104, respectively, connected by means of mobile routers 110 and 112 located in respective 6LoWPANs 101 and 103. As shown in FIG. 1, the mobile router 110 operates in WLAN mode to connect to an access point (AP) 120 defining a WLAN 102, and, with respect to 6LoWPAN 103, the mobile router 112 operates in ad hoc mode to connect to a mobile router 141 or 142 defining a mobile ad hoc network (MANET) 104. The AP 120 is connected to the Access Router 130 of the IPv6 network, and the mobile routers 141 and 142 of the MANET are connected to the Access Router 132 of the IPv6 network via a gateway 140. The access network connection mode of the mobile routers 110 and 112 of 6LoWPANs 101 and 103, respectively, determines their egress interface. That is, when the egress interface of a mobile router is configured to an IEEE 802.11 WLAN mode, the mobile router establishes a connection to an AP of an IEEE 802.11 WLAN, the AP being connected to an access router of the IPv6 network. Otherwise, when the egress interface of a mobile router is configured to an IEEE 802.11 ad hoc mode, the mobile router establishes a connection to a gateway of a MANET via one of the mobile routers constituting the MANET, and the gateway being connected to an access router of the IPv6 network. The mobile routers of the MANET can establish links among each other and connect to the access router of the IPv6 network via the gateway of the MANET without involvement of an AP.
In the network environment having multiple 6LoWPANs, as shown in FIG. 1, a 6LoWPAN may also be connected to another 6LoWPAN, rather than to a WLAN, for accessing the IPv6 network, and this situation causes significant network problems due to the excessive overhead to the nodes inappropriate for accommodating a mobility protocol and limited packet size. Accordingly, there is a need to develop an efficient mobility management technique that is appropriate for 6LoWPAN networks and capable of overcoming these network problems caused by using the conventional mobility protocol.